Efficacy and tolerability are important factors determining the choice of a medication for treatment of mental depression and other mental disorders including Functional Somatic Disorders. The move from tricyclic antidepressants (TCAs) to selective serotonin reuptake inhibitors (SSRIs) involved not only the loss of the direct receptor interactions responsible for the adverse side effects of TCAs, but also the loss of the ability to inhibit the reuptake of norepinephrine. Selectivity for the single neurotransmitter serotonin may explain why SSRIs tend to be less efficacious than TCAs, especially in more severe forms of depression (Lopez-Ibor J. et al., 1996, Int. Clin. Psychopharm., 11:41-46). Older TCAs are associated with significant behavioral toxicity, notably psychomotor and cognitive impairment and sedation, SSRIs are largely devoid of these effects, but gastrointestinal disturbances such as nausea and dyspepsia are common with these agents (Hindmarch I., 1997, Human Psychopharmacology, 12:115-119). For example, for the widely prescribed SSRI sertraline (Zoloft®, Pfizer), the three most common adverse events associated with discontinuation of treatment were nausea, insomnia, and diarrhea (Physician's Desk Reference, 57th Edition, 2003, Thomson Medical).
Efforts toward improving antidepressant medications are guided by cumulative evidence from neurochemical and clinical studies supporting the therapeutic potential of enhancing monoamine function in depression. A number of antidepressant drugs have been developed based on their interaction with both serotonin (5-HT) and norepinephrine (NE) receptors. These serotonin and norepinephrine reuptake inhibitors (SNRIs) include duloxetine, venlafaxine, and milnacipran. Milnacipran is more appropriately referred to as a norepinephrine and serotonin reuptake inhibitor (NSRI) since its norepinephrine (“NE”) to serotonin (“5-HT”) ratio is 2:1 (Moret et al., 1985, Neuropharmacology, 24:1211-1219; Palmier et al., 1989, Eur. J. Clin. Pharmacol., 37:235-238). Current clinical evidence suggests that these new agents may offer improved efficacy and/or faster onset of action compared with SSRIs (Tran P. V. et al., 2003, J. Clin. Psychopharmacol., 23:78-86). Recent trials with the NSRI milnacipran suggest that this compound is effective in relieving pain both associated with, and independent of, depression (Briley M., 2003, Curr. Opin. Investig. Drugs, 4:42-45; Cypress Bioscience Inc., Cypress Bioscience Inc. Announces Final Results of Milnacipran Phase II Clinical Trial in Fibromyalgia, Media Release, Mar. 21, 2003, Available from: URL: (http://www.cypressbio.com).
Unfortunately these SNRI and NSRI compounds have demonstrated numerous side effects in human clinical trials. For example, the safety and tolerability of duloxetine (Cymbalta®, Eli Lilly and Company) was assessed in a pooled analysis of 7 double-blind trials involving 1032 patients treated with duloxetine (40-120 mg/day) and 732 patients treated with placebo. Adverse events which occurred at a rate of more than 5% for duloxetine were nausea, dry mouth, fatigue, dizziness, constipation, somnolence, decreased appetite, and sweating. Adverse events which led to discontinuation of treatment were nausea, dizziness, somnolence, dermatitis, insomnia, headache, and fatigue. Nausea and dizziness led to significantly more duloxetine-treated patients discontinuing treatment, compared with placebo (Mallinckrodt C. et al., American Psychiatric Association 2002 Annual Meeting, New Research Abstracts, 119, May 18, 2002; Detke M. J. et al., American Psychiatric Association 2002 Annual Meeting, New Research Abstracts, 33-34, May 18, 2002). Nausea was the only adverse event reported as a reason for discontinuation (Eli Lilly and Company, New Research Shows Cymbalta Reduces Anxiety Symptoms Associated with Depression, Media Release: Sep. 18, 2003).
For venlafaxine (Effexor®, Wyeth-Ayerst), a member of the SNRI family, the major reported side effects were those that affected the gastrointestinal system. In 4- to 8-week placebo-controlled clinical trials, treatment-emergent major gastrointestinal adverse experience incidence for Effexor® versus placebo (n=1,033 vs. 609) were: nausea (37% vs. 11%), constipation (15% vs. 7%), anorexia (11% vs. 2%), and vomiting (6% vs. 2%). In the same clinical trials, treatment-emergent major central nervous system adverse experience incidence were: somnolence (23% vs. 9%), dry mouth (22% vs. 11%), dizziness (19% vs. 7%), insomnia (18% vs. 10%), nervousness (13% vs. 6%), anxiety (6% vs. 3%), and tremor (5% vs. 1%). Importantly, nausea, in addition to being the most common reported side effect (see above), was the top reason venlafaxine patients in Phase 2 and Phase 3 depression studies discontinued treatment: almost 32% of patients who discontinued treatment did so due to nausea (Physician's Desk Reference, 57th Edition, 2003, Thomson Medical).
Milnacipran (Ixel®, Pierre Fabre), has demonstrated numerous adverse reactions in human clinical trials with tolerability decreasing with increasing dose (Puech A. et al., 1997, Int. Clin. Psychopharm., 12:99-108). In the double-blind, randomized, multicenter clinical study the most frequent spontaneously reported adverse events for 100 mg/day milnacipran twice daily were as follows: abdominal pain (13%), constipation (10%), and headache (9%). Interestingly, when in the same study milnacipran was given 200 mg/day twice daily, pain related adverse reactions decreased (headache to 8% and abdominal pain to 7%) but nausea and vomiting were more pronounced side effects and were reported by 7% of the patients (Guelfi J. D., 1998, Int. Clin. Psychopharm., 13:121-128). In a double-blind comparative study involving 219 elderly patients with depression the only adverse event reported more frequently for milnacipran recipients than for TCA imipramine recipients was nausea. Patients received either milnacipran or imipramine 75-100 mg/day twice daily for 8 weeks (Tignol J. et al., 1998, Acta Psychiatrica Scandinavica, 97:157-165). It was also observed that when milnacipran was administered intravenously to 10 patients, five of them reported transient nausea. Nausea was primarily reported at the moment of peak of milnacipran plasma level (Caron J. et al., 1993, Eur. Neuropsychopharmacol., 3:493-500). This study clearly demonstrates that nausea is directly correlated with milnacipran blood plasma concentration. In addition, it strongly suggests that the nausea can be a centrally mediated side effect since the drug was given intravenously in this study. Data from other studies suggest that milnacipran may also induce a locally mediated nausea via gastric irritation (the rapid onset of the nausea was observed even prior to achieving peak plasma levels).
The incidence of spontaneously reported milnacipran adverse experiences in placebo-controlled clinical trials is given in Table 1 (adverse effect is listed if frequency was more than 2% in milnacipran 100 mg/day group). It is clearly seen from the data presented in Table 1, that the incidence of certain adverse events, including nausea, vomiting, sweating, hot flashes, palpitations, tremors, anxiety, dysuria, and insomnia, increase with dosage.
TABLE 1Incidence of spontaneously reported milnacipran adverseexperiences in placebo-controlled clinical trialsFrequency of Adverse Experiences (%)50 mg/day100 mg/day200 mg/dayAdversePlacebotwice dailytwice dailytwice dailyEventN = 394N = 426N = 1871N = 865Nausea10.912.711.219.4*Headache17.014.68.413.5Increased1.314.04.3*11.6*SweatingConstipation4.38.06.511.4*Insomnia10.79.26.111.3Dry mouth5.69.47.99.0Vomiting3.63.83.97.9*Abdominal Pain5.16.16.57.6Tremor1.50.92.56.7*Anxiety1.32.84.15.1Palpitations1.82.32.74.6Vertigo1.81.65.04.5Fatigue3.02.82.54.4Dysuria0.31.42.1*3.7*Hot flushes01.63.03.6Somnolence3.85.42.33.5Agitation3.01.63.32.9Nervousness2.04.22.02.8Dyspepsia4.13.52.12.2**Significantly greater than placebo
It is important to note that in one of the early depression trials, even after one week of milnacipran dose escalation employed to reduce side effects, the most commonly reported reason for discontinuation of treatment because of adverse effects was nausea and vomiting (Leinonen E., 1997, Acta Psychiatr. Scand., 96:497-504). In the recent fibromyalgia clinical trial with the long dose escalation period (four weeks), which was implemented in order to reduce milnacipran side effects and increase patient's tolerance, the most common dose-related side effect reported by patients was nausea (Cypress Bioscience Inc., Cypress Bioscience Inc. Announces Final Results of Milnacipran Phase II Clinical Trial in Fibromyalgia, Media Release, Mar. 21, 2003).
The data presented in Table I demonstrates that the currently available immediate release formulation of milnacipran is not ideal for the treatment of medical conditions that require milnacipran doses equal or above 100 mg/day given either once a day or twice a day due to high incidence of treatment-emergent side effects that leads to poor patient tolerance. Higher doses are required in the treatment of severe depression and other associated disorders. As shown in one of the early antidepressant clinical trials, milnacipran dosages of 200 mg/day were superior to lower doses (Von Frenckell R et al., 1990, Int. Clin. Psychopharmacology 5:49-56). Milnacipran dosing regimes of 100-250 mg daily were recently reported for the treatment of fibromyalgia (U.S. Pat. No. 6,602,911). It would be very difficult to reach the upper limits of the dose range using the currently available formulation due to the dose related treatment emergent side effects and the need to titrate over a long period of time to reach the required dose.
Moreover, an immediate release formulation of milnacipran may not be suitable for a once-daily dosing regimen for treatment of depression due to milnacipran's relatively short half-life, which is approximately 8 hours, (Ansseau M. et al., 1994, Psychopharmacology 114:131-137). Milnacipran's relatively short half-life could also be responsible for the observation that twice-a-day administration (versus once-a-day) of immediate release formulation in fibromyalgia trials resulted in pain improvement statistically superior to that of placebo treatment (Cypress Bioscience Inc., Cypress Bioscience Inc. Announces Final Results of Milnacipran Phase II Clinical Trial in Fibromyalgia, Media Release, Mar. 21, 2003).
Merely stating that a drug can be administered using a sustained release formulation is not sufficient. For example, U.S. Pat. No. 6,602,911 to Kranzler et al. states “for administration orally, the compounds may be formulated as a sustained release preparation”. While the above patent references formulation techniques, only WO98/08495 by Paillard B. et al. provides specific sustained release formulations of milnacipran. However, Paillard does not describe diminishing locally and/or centrally mediated side effects. Only by careful understanding of the relationship of the therapeutic dose to plasma levels can a modified dosage form be designed that will reduce, diminish, or prevent locally mediated as well a centrally mediated side effects. Paillard describes a prolonged release formulation of milnacipran with dosages ranging from 60-240 mg, in which 10-55% of the total dose is released within two hours. The prolonged release formulation consists of saccharose and/or starch minigranules coated with the active drug and then coated with at least one water-insoluble polymer that is permeable to physiological fluids.
U.S. Pat. No. 6,066,643 to Perry describes a method of potentiating the therapeutic action of an SSRI, for example milnacipran, by coadministering the SSRI with monoxidine. Perry suggests alleviating or diminishing side effects of a SSRI by co-formulating an SSRI in a “quick, sustained, or delayed release” formulation with a centrally acting antihypertensive agent. The administration of the latter compound to humans is associated with drowsiness, headache and dry mouth. Perry's approach may result in additional side effects experienced by patients.
It is therefore an object of the present invention to provide milnacipran formulations which will lower the incidence and intensity of side effects, especially for higher dosages, and lower or reduce the frequency of dosing and the need to slowly titrate the drug in order to achieve the therapeutic dose levels required for treatment of these disorders.
It is therefore an object of the present invention to provide milnacipran formulations that produce a therapeutic effect over approximately 24 hours when administered to a patient in need, wherein the release rate and dosage are effective to provide relief from at least one disorder selected from the group consisting of depression, fibromyalgia syndrome, chronic fatigue syndrome, pain, attention deficit/hyperactivity disorder, and visceral pain syndromes (VPS) such as irritable bowel syndrome (IBS), noncardiac chest pain (NCCP), functional dyspepsia, interstitial cystitis, essential vulvodynia, urethral syndrome, orchialgia, affective disorders including depressive disorders (major depressive disorder, dysthymia, atypical depression) and anxiety disorders (generalized anxiety disorder, phobias, obsessive compulsive disorder, panic disorder, post-traumatic stress disorder), premenstrual dysphoric disorder, temperomandibular disorder, atypical face pain, migraine headache, and tension headache, with diminished incidence or reduced intensity of common milnacipran side effects reported for immediate release formulation.
It is a further object of the present invention to provide formulations that provide alternative pharmacokinetic release profiles that eliminate or diminish unwanted side effects and the current need to slowly increase (titrate) doses in order to achieve the desired therapeutic dose.
It is still another object of the present invention to provide a formulation that provides a unit dose between 25 and 500 mg which provides for flexibility in morning or evening administration.